(1) Field of the Invention
This invention relates to a substrate support structure for supporting substrates such as semiconductor wafers, glass substrates for liquid crystal displays, glass substrates for photomasks and substrates for optical disks (hereinafter simply called “substrates”), a first sheet-like object for use in the substrate support structure, a method of manufacturing the substrate support structure, a heat treatment apparatus for heat-treating the substrates, and a substrate sucking method for sucking the substrates.
(2) Description of the Related Art
As requirements for fine line width and line width uniformity of patterns formed on substrates have become increasingly stringent in recent years, a strong demand is being placed for temperature uniformity in baking treatment in photolithography, especially in baking treatment after exposure (PEB: Post Exposure Bake).
Thus, a heat treatment apparatus has been proposed that heat-treats substrates supported by suction (as disclosed in Japanese Unexamined Patent Publication H10-284360 (1998), for example). This heat treatment apparatus has metallic projections formed on the upper surface of a heat-treating plate and coated with resin. These projections constitute a substrate support structure for contacting and supporting each substrate. The heat-treating plate has a ring-like sealer disposed on the upper surface thereof for contacting edge regions of the substrate. Further, exhaust bores are formed to extend through the upper and lower surfaces of the heat-treating plate for exhausting gas. When a substrate is placed on the substrate support structure, a closed space is formed between the substrate and heat-treating plate. Gas is exhausted from this space through the exhaust bores, thereby to apply suction to the substrate. By sucking the substrate in this way, any curvature of the substrate is corrected to heat the substrate uniformly.
The conventional apparatus noted above has the following drawback.
Since the projections that contact the substrate are metal as is the heat-treating plate, heat is transferred mainly through the projections to the substrate supported by the substrate support structure. This results in an inconvenience of a great difference in heat history over the substrate surface occurring between areas in contact with the projections and other areas.